Façade specification in England is changing. It is not simply individual products, insulation materials or external wall systems that are under greater scrutiny. The regulatory environment increasingly requires designers and contractors to demonstrate how the complete external wall system has been designed, specified and controlled throughout construction.
Two developments illustrate this particularly clearly: the 2026 review of Approved Document B and the Building Safety Regulator's Gateway 2 process for higher-risk buildings.
Together, they reinforce the importance of taking a complete system approach to façade specification, supported by appropriate technical evidence and project-specific design.
Approved Document B 2026: external walls remain under scrutiny
The Government's 2026 review of Approved Document B: Fire Safety includes proposals affecting external wall systems and balconies, combustible materials in and on external walls, existing buildings and other aspects of fire safety guidance.
The consultation includes proposals to revise and update guidance relating to external wall systems and balconies and review the scope of the ban on combustible materials in and on external walls and specified attachments.
Importantly, these proposals should not be presented as current statutory requirements unless and until they are formally adopted.
However, they demonstrate the direction in which façade and external wall regulation continues to move: towards greater scrutiny of the complete wall construction, its individual components and the way those components interact with the wider building.
For façade designers and specifiers, understanding the complete system is therefore increasingly important.
What does Gateway 2 mean for façade specification?
For higher-risk buildings in England, building control approval must be obtained from the Building Safety Regulator (BSR) before relevant building work begins.
This stage of the building safety regime is commonly referred to as Gateway 2.
The process requires sufficient information to demonstrate how the proposed work will comply with the Building Regulations and how compliance will be managed throughout the project.
For façade designers, manufacturers, specifiers and contractors, this has an important consequence.
The external wall can no longer be treated as a loosely defined collection of products that can be readily changed during construction without considering the wider implications.
Once building control approval has been granted, the documents submitted as part of the application become the project's agreed documents. Changes to these documents are controlled changes and must be assessed and recorded through the project's change-control process.
Depending on the nature and significance of a proposed change, it may also need to be notified to or approved by the Building Safety Regulator before associated work proceeds.
Why façade product substitution matters
Product substitution has long been a feature of construction projects. Availability, programme pressures, cost and procurement can all create reasons to consider an alternative product.
Under the new building safety regime, however, seemingly straightforward substitutions require careful technical consideration.
Imagine a specified external wall or façade system containing:
- mineral wool insulation
- a particular carrier or sheathing board
- mechanical fixings
- reinforced basecoat
- reinforcing mesh
- membranes
- cavity barriers
- specific interface details
- a silicone render finish
Changing one component may appear commercially minor.
From a technical perspective, however, a substitution could potentially affect characteristics such as:
- fire performance
- moisture behaviour
- wind resistance
- dead load
- fixing performance
- movement accommodation
- component compatibility
- interface detailing
- certification or assessment scope
The Building Safety Regulator's change-control guidance makes this particularly relevant for higher-risk buildings.
Changes to external walls can constitute a major change, while replacing a product with one that has a different reaction-to-fire specification may also trigger specific change-control requirements.
Product substitution should therefore be considered in the context of the complete approved façade design, rather than looking at an individual product in isolation.
External walls need a system approach
This regulatory direction reinforces the importance of treating external wall insulation and façade solutions as complete systems.
For example, Baumit's current Kiwa Agrément for StarSystem Mineral – Direct Fix defines the solution as a mechanically and adhesively fixed mineral wool external thermal insulation composite system (ETICS) and identifies the integral components that form the assessed system.
Its scope includes defined masonry and concrete supporting walls, as well as externally sheathed light-gauge steel frame walls, subject to the conditions and limitations set out within the certification.
This is an important distinction.
Third-party certification provides evidence relating to the assessed system and its defined scope, but it does not replace project-specific façade design.
The suitability of a system still needs to be assessed against the individual building, substrate, exposure, structural requirements, interfaces and other relevant project conditions.
Certification and project-specific façade design
A certified external wall system provides an important foundation for specification, but certification should always be understood within its defined scope.
A façade specification should consider factors including:
- supporting wall construction
- substrate condition
- building height and geometry
- wind loading
- fixing design
- fire performance requirements
- moisture management
- movement
- openings and penetrations
- interfaces with windows and doors
- rooflines and parapets
- cavity barriers and fire-stopping
- compatibility between system components
- exposure and weather conditions
These considerations demonstrate why simply specifying "mineral wool EWI with silicone render" is increasingly inadequate for complex façade projects.
The complete system, its evidence and its relationship with the wider building need to be understood.
Five questions for modern façade specification
As regulatory scrutiny increases, a modern façade specification increasingly needs to answer five fundamental questions:
- What exactly is being installed?
The complete system and its components should be clearly defined. - Where is it being installed?
The building, substrate, height, exposure and relevant project conditions need to be understood. - What evidence supports its use?
Certification, testing, assessments and other technical evidence should be appropriate to the proposed application. - How does it interface with the rest of the building?
Openings, fire barriers, penetrations, rooflines, adjoining construction and other interfaces must form part of the design. - What happens if somebody wants to change it?
Proposed substitutions need to be technically assessed and, on higher-risk buildings, managed in accordance with the project's formal change-control requirements.
Gateway 2 is changing the role of façade manufacturers
The changing regulatory environment also has implications for the relationship between manufacturers and project teams.
For façade and external wall system manufacturers, the role is increasingly moving beyond simply supplying individual products.
Designers and contractors need access to clearly defined systems, appropriate certification, technical information, installation guidance and support that allows them to demonstrate why a particular solution is suitable for its intended application.
This makes early engagement between architects, façade designers, contractors and system manufacturers increasingly valuable.
The future of external wall and façade specification
Approved Document B, Gateway 2 and the wider building safety regime point towards a more rigorous approach to external wall specification in England.
The question is no longer simply:
"Which insulation and render should we use?"
Instead, project teams increasingly need to demonstrate:
What is the complete system? Where can it be used? What evidence supports it? How has it been designed? And how will any changes be controlled?
For façade manufacturers, this reinforces the importance of moving from product supplier to technical system partner, helping project teams specify complete, appropriately evidenced solutions from design through to installation.
Further reading: UK Government – Building control approval for higher-risk buildings and Review of Approved Document B: Fire Safety.